In the manufacture of many products, heat exchangers for example, there is a need for large quantities of lengths of material such as tubes are cut to a very precise length with their ends accurately perpendicular to the axis of the tube. Machines for cutting such tubes to length have been provided heretofore. From the standpoint of economy it is a practical necessity that such machines are capable of cutting tubes while the tubing is moving in a rectilinear path at a relatively high velocity, preferably as the tubing is exiting from the last form roll of a tube mill. Thus, such machines invariably employ a slide of some type on which the cut-off device is mounted and a means for moving the slide at the same speed as the tube during the severing operation. Heretofore complicated and costly devices have been employed for synchronizing the speed of the tube drive means and the speed of the slide on which the cut-off device is mounted. These means have been primarily electrically or air operated. Such synchronizing devices have been not only expensive, but also incapable of functioning accurately when the tube speed is in excess of about 175 feed per minute.
In my prior U.S. Pat. No. 4,462,290, a tube cut-off unit is arranged at the downstream end of a tube mill and is powered by a drive unit mechanically driven by the main shaft of the mill which drives the tube forming rolls. The drive unit mechanically rotates a crank which, through a link, reciprocates a slide along the path of travel of the tube. A tube cut-off blade on the slide is cam actuated to sever the tube. Means are provided to insure that the slide is moving at a constant speed and at the same speed as the tube when the tube is being severed.
Among the objectives of the present invention are to provide a cut-off machine for severing a plurality of lengths such as tubes from a moving length; which severing operation is conducted while the tubing is moving from a mill; which utilizes a novel cut-off assembly; which has minimum wear; and which can be adjusted for varying lengths of tube while the machine is operating.
In accordance with the invention, the cut-off machine comprises a cut-off machine for cutting off predetermined lengths from a moving length of roll form material such as tubing adapted to be positioned downstream from a source such as a tube mill for receiving a moving length from the mill and severing plural predetermined lengths from the moving length. The machine comprises a plurality of cut-off assemblies which are reciprocated longitudinally of the moving length of material formed by the mill and operated during the movement to sever plural predetermined lengths. The reciprocating and cutting movements are mechanically derived from a motor driven in synchronism with the speed of movement of the moving length. The apparatus includes mechanisms that permit the length of the tubes to be changed while the machine is operating.